Radio traffic control system



S p 27, 1938. w. SHALSTEAD 2,131,042

RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10 SheetsSheet 1 IN VEN TOR. Maw/v 6. WASTE/m Sept. 27, 1938. w. s. HALSTEAD ,0

RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10 Sheets-Sheet 2 ,{y.6 INVENTOR. Mill/W J. #4157544 ATTORNEY Sept. 27, 1938. w. s. HAL STEADRADIO TRAFFIC CONTROL SYSTEM Filgd Sdpt. 28, 1935 l0 Sheets-Sheet 3Sept. 27, 1938. w. s. HALSTEAD 2,131,042

RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10- Sheets-Sheet 4Muwmd #4467671 Sept. 27, 1938.

w. s. HALSTEAD RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10Sheets-Sheet 6 p 1938. w. s. HALSTEAD 2,131,042

RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10 Sheets-Sheet '7srop /a5 *6. Maw/V701 Miami/mama ATTORNEY:

Sept. 27, 1938.

w. s. HALSTEAD 2,131,042 RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28,1935 l 0 Sheets-Sheet 8 [N VEN TOR. Wax/mu. #7157020 d' 6 n ATTORNEYSept. 27, 1938. w. 's. HALSTEAD 2,131,042

RADIO TRAFFIC CONTROL SYSTEM Filed Sept.- 28, 1955 10 Sheets-Sheet .9

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i l l D I 1V 1 W---E I s INVENTUR Mil/HM S. mama ijz 28 BY ATTORNEYSept. 27, 1938. w. s. HALST EAD 2,131,042

RADIO TRAFFIC CONTROL SYSTEM Filed Sept. 28, 1935 10 Sheets-Sheet 10 :11 W WM Mam/J. #9157090 54, OQA'QM Patented Sept. 27, 1938 mnro memocomm. SYSTEM William S. Halstead, New York, N. Y.

'REISSUED Application September 28, 1935, Serial No. 42,703 '1 Claims.(c1. 117-337) My invention relates, in general, to traflic con- 'trolsystems and is more particularly concerned with systems for controllingthe movement of behicular traflic by directional radio signalling means.

My invention is particularly applicable to trafflc control systemsinwhich colored lights or moving semaphore arms serve as signals forcontrolling the movement of traflic on various parallel or intersectinglanes, such as is the case in railroad and automobile traflic controlsystems respectively; but it will be readily understood that thisparticularization constitutes no limitation on the invention which mayalso be employed in many applications apart from that outlined.

Heretofore in the majority of traffic" control systems it has beencustomary to employ colored lights or other visible signalling devicessuch as moving semaphore arms or discs to indicate to the operator of amoving vehicle that he should continue in his course, change speed, or'stop at predetermined points. Since the efilciency of operation of suchvisual devices is subject to objectionable. variations because of poorvisibility commonly encountered in snow, rain, dust storms and fogwherein the'range of visibility is serious- 1y limited, the degree ofcontrol .of such signaling devices is uncertain and in many casesentirely ineffective. major causes of railroad and highway accidentsduring storms has been through the lack of reception of a stop signal bythe driver because of his restricted range of vision. With presentautomobile traflic control systems, especially,

many accidents have been caused by inability of the driver to see thecontrol light in time because of heavy trafilc which requires the fullattention of the driver, unfamiliarity with the location of the signals,confusion with other lights, or the blinding efl'ects of sunlight inlate afternoon when on a highway leading in the direction of sunset.

It is a primary object of the present invention to provide dependableand comparatively simple means by which the directional quasi-opticalcharacteristics of wave propagation from an ultra-high frequency radiotransmitter cooperatively associated with a traflic signal controldevice are employed to effect selective operation of a predeterminedsignal connected with an ultra-high frequency radio receiver installedin a moving vehicle proceeding towards the radio signal source.

It is 'an additional object to my invention to provide means by whichpredetermined changes It is well known that one of the in thecharacteristics of a polarized quasi-optical radio wave are effected incorrelation with predetermined changes in the visual signals of atraflic control device employing colored lights or moving signalindicating media.

, 5 Another object of my invention is to provide means by whichpredetermined changes in the modulating characteristics of a polarizedultrahigh frequency radio wave are effected in correlation withpredetermined changes in the character of visual signals of a trafiiccontrol device employing colored lights or other visible signallingmedia.

It is a further object of my invention to provide a uni-directionalultra-high frequency radio tramc control system which will be unafiectedby atmospheric conditions and which will cause no interference withcommunication services such as television and broadcasting onsubstantially the same or adjacent ultra-high. frequency radio channels.j

Another object of my invention is to provide a simple construction ofdirectionally selective ultra-high frequency radio receiving apparatusadapted to be mounted on a moving vehicle for quency radio transmissionapparatus. synchro nized in operation with a traflic light orsemaphoresystem for reproducing in the vehicle, visual and audible indicationscorresponding tothe character of the visual signal from the trafliclight or semaphore.

A further object of my invention is to provide a construction ofultra-high frequency radio transmitting equipment which may be readilymounted on conventional types of trafllc control devices without thealteration of such devices, for the purpose of emitting radio controlsignals to operate signal indicating devices within automobiles,railroad trains, or other moving vehicles.

A still further object of my invention is to pro;

,Vide means whereby telephonic traflic control messages, policedepartment warnings, highway directions, standard time signals,advertising, or otherintelligence may be transmitted to the interior ofa moving vehicle simultaneously with the emission of-trafli'c signals byan ultra-high frequency radio transmitter.

Other and further objects of my invention reside in the constructionaland circuit arrangements for directional ultra-highfrequency radiosignal emitting devices associated with trafflc control devices andultra-high frequency radio signal receiving devices installed onarailroad train, automobile or othervehicle, as set forth cooperationwith directional ultra-high frefully in the specification hereinafterfollowing. and by reference to the accompanying drawings in which: i

- Figure 1 is a front elevational view of a rail- Dhore arm, therebyeffecting changes in the polarization characteristics of the emittedradio wave in accordance with correlated changes in the character of therailroad signal.

Figure 2 is a side elevational view of the same signal semaphore withthe ultra-high frequency oscillator and dipole antenna disposed in theposition shown in Figure 1.

Figure 3 is an elementary schematic diagram of the ultra-high frequencyoscillator and dipole I antenna, illustrating the degree of angularrota- I tion effected by the longitudinal axis of the antenna inaccordance with similar angular changes in the signalling positions ofthe semaphore arm, thereby effecting changes in the polarizationcharacteristics of the emitted wave.

Figure 4 is an elementary schematic diagram of one form of polarizedmicrowave radio re- I ceiver and associated signal indicating systemembodied in my invention for use in cooperation with the polarizedmicrowave transmitter of the preceding figures, and shown herewith toaid in illustrating the principle of operation of the sys-' tem anddevices of my invention. I

I Figure 5 is a schematic diagram in simple isometric projection, toillustrate the operative coordination between the horizontal position ofthe dipole antenna when the semaphore arm is in the .horizontal stopposition, and the horizontal receiving dipole connected with anultrahigh frequency detector and signal indicating device installed in amoving vehicle, to give visual and audibleindication therein of thecharacter of the semaphore signal.

Figure 6 is'a schematic diagram of the vertical receiving dipole withassociated dectector and signal indicator shown in Figurev 4,illustrating the effective reception of a vertically polarizedultra-high frequency signal by the vertical receiving dipole when thetransmitting dipole is in an approximately vertical positioncorresponding to the vertical or go position of the semaphore arm, aswill be explained hereinafter.

I Figure '7 is a schematic diagram' of one embodiment of an ultra-highfrequency radio receiving system, installed in the cab. of a locomotiveor other moving vehicle, which employs automatiemeans to change theangular position of the longitudinal axis of the receiving dipole withrespect to the position of the transmitting dipole,

and simultaneously to select particular segments of a commutatoroperatively coordinated with particular positions of the receivingdipole, thereby providing selective control of signal lights in thevehicle, orautomatic power and brake control if desired, in accordancewith the character of the semaphore signal as will be explainedhereinafter. 1

Figure 8 is a. circuit diagram of one iorm of ultra-high frequencydetector circuit employed in a receiving system of the type shown are 7.

in Figfrequency oscillator and dipole antenna unit Figure 9 is a planview of one form of ultrahigh frequency oscillator and dipole antennaunit, enclosed in a weatherproof housing, as embodied in my invention.

Figure 10 is a. front elevational view of the device shown in Figure 9,a vertical cross section being taken along lines A'--A and B- -B asshown, to illustrate the preferred arrangement of parts within'th'eprotective housing of said oscillator and dipole antenna. I I 1 Figure11 is a circuit diagram of the ultra-high frequency oscillator anddipole antenna embodied in the unit shown in Figures 9 and 10.

Figure 12 is a front elevational view of a modiflcation of theultra-high frequency radio trafiic control device previouslyillustrated, showing the employment of a fixed ultra-high frequencyoscillator unit'having a horizontal dipole antenna disposed on aconventional form of automobile tramc control housing in which signallights are employed "to control the movement of traflic at intersectingstreets, the ultra-high frequency oscillator "and dipole antenna unit inthis case being installed on the top of the traffic light housing, withthe longitudinal axis of the horizontal dipole extending in a directionat right angles to the direction of trafll'c controlled by the signallights so as to effect correlated directional radio signal control oftraiiic as hereinafter explained. The same figure also illustrates thecooperative combination of a telephone system and a repeatingtelegraphone or other continuously operating sound-record reproducingmeans with the ultra-high frequency oscillator and dipole antenna unitto effect, in addition to the transmission of traflic control signals,the transmission of police messages and other in-- telligence to theinterior of automobiles or other moving vehicles equipped with theultra-high frequency receiving apparatus embodied in the invention.

Figure 13 is a plan view of the ultra-high frequency oscillator anddipole antenna unit disposed on the top of the traflic control deviceillustrated in Figure 12.

Figure 14 is a front elevational view of the ultra-high frequencyoscillator and dipole antenna unit of Figures 12 and 13, showing, inthis I case, the demountable attaching means employed in this embodimentof the invention for securing the ultra-high frequency transmitting uniton the top of a conventional traflic light housing.

Figure 15 illustrates, in an elevational view, the interior of anautomobile equipped with the directionally selective ultra-highfrequency receiver 3 and associated signal indicativedevices embodied inthe invention, and shows in particular a preferred location ofahorizontal receiving dipole and ultra-high frequency detector on thefront of the vehicle;

Figure 16 is a schematic diagram illustratingthe directionally selectivemode of operation of the ultra-high frequency trafllc control systemwhen employed in connection-with tramc lights located at a streetintersection.

Figure 17 is a schematic diagram of a traific control signal lightcircuit and the coordinated ultra-high frequency signal controlcircuits, illustrating the use of a plurality 'of modulating frequenciesto modulate the radio energy wave emitted by the ultra-highfrequencytransmitter,

each modulating frequency being indicative of a particular color of itscoordinated trafllc light,

Figure 18 is a circuit diagram of an ultra-high of the type employed inthe illustrated embodiment of the invention, together with a schematicdiagram of the associated ultra-high frequency modulating andcoordinated tramc control cir- 'cuits. This figure also shows thecooperative combination ofa telephone system and a repeatingtelegraphone to effect speech modulation of the emitted ultra-highfrequency signal.

Figure 19 is a front elevational view of the upper portion of anautomobile to illustrate the preferred disposition of a horizontalreceiving dipole and detector unit on the exterior of the vehicle, theinstallation in this case being located on the front of the vehicle justabove the windshield, which location has distinct functional ad-vvantages-as will be explained hereinafter.

Figure 20 is a side elevation of the same vehicle showing the horizontalreceiving dipole and detector unit illustrated in front elevation.of'Figure 19.

Figure 21is a circuit diagram of one form of ultra-high frequencyreceiver, amplifier, and associated signal indicating means employed ina vehicle to give audible and visual indication of the character of thetraffic control signal ahead of the vehicle.

Figure 22 is a schematic diagram of a simplified modification of theultra-high frequency receiving apparatus illustrated heretofore in whichan ultra-high frequency detector unit is employed in connection with aconventional automobile broadcast receiver to give indication of thecharacter of a trafiic control signal. v

Figure 23 is a front elevational view of a railroad signal equipped witha modification of the ultra-high frequency signalling system heretoforeillustrated, wherein an ultra-high frequency oscillator and horizontaldipole antenna are, disposed in a fixed position on the top of thesignal support in front of a metallic reflector to eifect unidirectionaltransmission of the ultra-high frequency signal. Figure 23 also showsthe cooper ative combination of a telephone circuit with the ultra-highfrequency oscillator whereby traffic instructions or other intelligencemay be transmitted to the interior of a locomotive cab in addition tothe transmission oflight control signals.

Figure 24 is a side elevation of the ultra-high frequency oscillator,dipole antenna, reflector, and signal light device shownin Figure 23.

Figure 25 is a front elevational view of a railroad signal lightequipped with an ultra-high frequency oscillator having a horizontaldipole antenna disposed in front of a reflector to control the responseof a horizontally polarized ultrahigh frequency receiver and associatedsignal indicator devices located in the cab. of a locomotive proceedingon a track controlled by the depicted signal.

Figure 26 is a front elevational view of another signal light equipped.with an ultra-high frequency oscillator having a vertical dipole antennafrequency signal devices illustrated in Figures 25 and 26, one of theultra-high frequency generators being equipped with a horizontal dipoleantenna, the other ultra-high frequency generator being equipped with avertical dipole antenna, thereby effecting selective control of thereceived signals in the cabs of the two locomotives proceeding onparallel tracks and in the same direc- Figure 30 is a schematic diagramof the ultra- A high frequency receiving dipole, detector, amplifier,loud speaker, electric wave filters and the signal lights associatedwith each of the filters for selectively effecting the operation of aparticular signal or signals in the cab of a locomotive, in accordancewith the reception of a particular ultra-high frequency signalcorrelated with the diiferent colors of the signal light.

Figure 31 is a circuit diagram of an ultra-high frequency receiver andassociated electric wave filters for effecting the selective operationof one or a plurality of signal lights installed in the cab of alocomotive in accordance with the particular modulating frequency orfrequencies of the received ultra-high frequency signal.

Referring to the drawings in detail, wherein like reference charactersindicate corresponding parts throughout the several views, each form ofthe invention illustrated herewith embodies quasi-op- .tical radio wavegenerating means such as provided by an ultra-high frequency,- radiooscillator, shown at I, Figures land 2, combined with a directionalpolarized wave-radiator, such as a dipole antenna 2 to operate incombination with and in correlation with the trafllc control signals ofa railroad, automobile or other signal system employing lights ofdifferent colors such as provided by lenses 3 and 4, a moving semaphorearm 5, or other signalling media to effect transmission of trafliccontrol signals to the interior of locomotives, automobiles or othermoving bodies equipped with microwave signal receiving and indicatingmeans embodied in the system of the invention. In the particularembodiment of the invention shown in Figure l, the ultra-high frequencyoscillator, I, and the dipole radiator, 2, are assembled as a singlecoaxial unit, the unit being so disposed on the semaphore arm 5, that acommon rotational axis, 6, is effected, as is illustrated in Figures 1and 2. A metallic shield, 1, may be employed behind the semaphore andultra-high frequency oscillator unit as shown to effectively prevent thetransmission of the ultra-high frequency signal in a direction oppositeto that of the projected light rays from the traflic signal.

In the particular embodiment illustrated herewith the shield, 1, takesthe form of a sheet metal disc, but it is obvious that other forms andtypes of shields or reflectors may be employed in lieu thereof. In theembodiment of the invention shown herewith ultra-high frequencyoscillator unit, I, is secured to the semaphore arm, 5, so that when thearm is in the horizontal position shown in Figure 1 the longitudinalaxis of the dipole, 2, also extends in a horizontal direction. It isevident, from the illustration of Figure 1, that when the semaphore arm,5, moves upward through angle 18 towards a vertical position, thedipole, 2, also moves through the same angle, as shown in Figures 1 and3.

In the particular embodiment of the invention depicted in Figures 1 and2 the heater and anode power supply for operation of theultra-highfrequency oscillator may be provided by a storage battery and a smallbattery-driven alternator, illustrated in subsequent figures. Since nomodulator or amplifier tubes need be employed in this particularembodiment of the invention wherein the oscillator is self-modulated bythe alternator supply, the comparatively minute current drain of anintermittently-operating ultra-high frequency oscillator permitsextended operation of the microwave transmitter by a singlestoragebattery.

As is well known in the radio art, an ultrahigh frequency dipoleradiator when disposed in a horizontal position as shown in Figure 1,will emit a radiant energy wave having horizontally polarizedcharacteristics. If a horizontally disposed receiving dipole, shown at8, Figures 4 and 5, installed on the front of a locomotive, approachesthe horizontally disposed and parallel transmitting dipole, 2, Figures-1and 5, the associated ultra-high frequency detector, 9, will supply areceived signal of maximum amplitude to amplifier l2, thereby effectingvisual actuation of a stop signal indicator, such as a red neon light,13, and audible energization of loud speaker l6. Simultaneously,ultra-high frequency detector, ll, Figure 4, connected to a verticallydisposed dipole, lll, installed on the front of the same locomotive,will deliver a signal of minimum amplitude to its amplifier, l4, and agreen signal indicator light, l5, by reason of insufficientenerglzation, will not be visibly actuated. When,

actuated. Novel means are thus provided by which discrimination betweentwo ultra-high frequency trafiic control signals is effected by virtueof differences in the plane of polarization of the ultra-high frequencyradio wave, each plane of polarization being correlated with aparticular signal of the traiiic controlling semaphore.

. In addition to the selective actuation of visual signals l3 and I5asdescribed heretofore, loud speaker l6, shown in Figure 4, connected tothe amplifiers l2 and It, will emit an audible warning signal in the cabof the locomotive to inform the driver of the proximity of a signalahead of the train. As long as the locomotive equipped with theultra-high frequency receiving apparatus embodied in the invention is infront of the semaphore the ultra-high frequency traflic signal will bereceived in the cab. Qnce the locomotive has passed the semaphore,however, there will be an abrupt termination of the signal in the cabsince the uni-directional quasi-optical wave propagation characteristicsof the antenna system limit its field to the area in front of thesemaphore. The unique directional characteristics of the ultra-highfrequency system therefore preclude the possibility that a trainproceeding in an opposite direction, for example, to the south, willreceive the ultra-high frequency signal intended for a northbound train.Should the southbound locomotive be in front of the signal set for thenorthbound train, the shielding effect of the locomotive itself issuflicient to prevent the reception of the ultra-high frequency signalby the receiver other than that for which the signal was intended, sinceit is assumed that the receiving dipole in each case will be installedat the front of the cab below the top of or on the front of thelocomotive. g

It is pointed out that ordinary short wave radio transmitters andreceivers would not emciently effect the purpose of the presentembodiment of the invention since short waves above several meters inwavelength lose many of the quasioptical characteristics possessed bythe ultra-high frequency system described herein. Moreover, the size ofan efficient antenna required by a transmitter operating on wavelengthsabove several meters would be sufiiciently great to preclude itsinstallation and use as described in connection with the presentembodiment of the invention. It will be understood therefore that thesystem of my invention is intended for operation with ultra-highfrequency waves of approximately 10 cm. to 1 m. in length, which havethe quasioptical characteristics prescribed.

In this connection also it might be noted that limitation of the rangeof the ultra-high frequency transmitter is effected quite simply, andlargely for the reason that the radiation pattern of the particular typeof low power transmitter involved has comparatively sharp terminationfringes. The limits of the radiation pattern for the transmitter in anylocation are determined and regulated with a standard receiver adjustedto effect light control above acertainthreshold signal value. Thus, onlyreceivers within a definitely limited area with respect to thetransmitter will respond sufficiently to efiect the desired controlfunction. In addition, as shown hereinafter, controlled relaysresponsive only to a single maximum signal and not to other signals oflesser intensity, which might be received at the same time may be usedin the receiver to insure reception of the proper traffic signal.

In a modification of the ultra-high frequency receiving system,heretofore described, the means shown in Figure 7 may be employed toeffect selection of red or green signal indicators, l3 and I5,respectively. In this modification a single dipole antenna ll, which maybe moved back I8 and an amplifier, l9, whose output is connected asshown through opposite and coacting commutator segments, 20-2! and 2228, respectively and movable segment selecting brushes M and 25 to redand green lights, l3 and I5, respectively is arranged as shown. Anelectric motor, 26, may be employed to slowly rotate through angle 3insulated shaft 21 to which are secured brushes, 24 and 25 and thedipole antenna, II. .when read in connection with the foregoingdescription of the manner of operation of the system and theillustrations of Figures 5, 6 and 7 in particular, it will be understoodthat when the receiving dipole, ll, of Figure '7 is in the horoizontalposition a horizontally polarized ultra-high frequency signal from ahorizontal transmitting dipole will be received with maximumintensity bydetector, l8, and associated amplifier, l9, rendered audible by loudspeaker, l6 and, by virtue of the disposition of the commutator segmentselective brushes 24 and 25 which eifect electrical contact betweensegments 20 and 2|, the signal lamp l3, correlated with segments 20 and2| will be energized and visually actuated. It is evident from thediagram of Figure 7 that so long as the commutatorsegment selectivebrushes 2t and 25 provide contact between coacting segments 20 and 2!,only the red lamp, I3, can be actuated, since no electrical contact iseffected between segment the operator of the locomotive will seeintermittent fiashes of red light i3 in the cab as the locomotiveapproaches the semaphore set in the horizontal stop position. On theother hand, if the semaphore arm and associated transmitting dipole areset in the vertical or "go position, de-

tector 18 will receive the vertically polarized ultra-high frequencysignal with maximum intensity when the receiving dipole I! is in thevertical position. Electrical contact simultane-' ously is made betweencoacting segments 22 and 23, thereby providing energizing voltage forthe green indicator light H5. The red light, i3, will not be energizedso long as the semaphore arm is in the vertical position, sincesubstantially no effective signal will be received by detector l8when-the receiving dipole I1 is in a horizontal position, therebyprecluding the possibility of energizing the red light l3 sufilcientlyfor its visible actuation. It is obvious that many modifications of theprinciple of operation of the system heretofore described are possiblewithin the scope of the invention. In lieu of the movabledipolereceivirig antenna as described, fixed dipoles extending at rightangles to each other may be employed and signal selection effected by'intermittently connecting each of the dipoles to the detector, andsimultaneously providing connection with the signal indicating deviceassociated with a particular dipole. It is also obvious that thereceived signal may beused automatically to actuate the power and brakecontrol system of the train as is schematically illustrated in dottedlines in Figure 7 by the provision of a timing device, 28, connectedwith a power and brake control relay, 29, both shown connected to thestop circuit of indicator lamp l3. Means are thus provided by which atrain may be automatically stopped within a predetermined time after ithas passed a stop signal.

It is also understood that many circuit modi-.

flcations of the ultra-high frequency receiver and transmitter arepossible within the scope of the invention, and many different types ofdetecting and oscillating circuits may be employed.

fQne present preferred ultra-high frequency detector circuit is showninl lgure 8 in which the two halves of. a receiving dipole areconnected, as illustrated, to the anode and grid of an ultrahighfrequency detector tube 30. Radio frequency chokes 3i and 32 areemployed in series in the anode and grid circuits, respectively, A

resistor, 33, is connected in series with grid choke, 32, to ground, towhich is also connected the cathode and one side of the heater circuitof the tube as shown. A condenser, 34, is shunted between the anodecircuit and the cathode as illusquency receiving or transmitting unit isshown in Figures 9 and 10 in which a cylindrical weatherproof housing,36, fabricated of porcelain, glass, Bakelite or other suitable material,is provided to completely enclose ultra-high frequency tube 30 used as amicrowave detector in this case, and its associated detector circuitelements such as chokes, 3i and 32, resistor, 33}, and other parts. Thedipole antenna, it, also is enclosed in a weatherproof cylindricalhousing,

3?, fabricated of non-conducting material such as porcelain, glass orother suitable material, which is secured to the housing, 36, by meansof insulating bushings or sleeves 38. A resistor, 39, Figure. 10, may beemployed if desired to provide suficient heat to the interior of thedipole and tube housing to prevent formation of excessive accumulationsof ice or moisture, the assembled unit being so constructed that warmair from the intsfior of tube housing, 35, may circulate within thedipole housing, 31. In the pre ferred arrangement illustrated herewith,the tube, 30, is so disposed in the central portion of housing, 36, thatthe anode and grid leads are substantially in line with the ends of thedipole thereby efiecting a highly desirable symmetrical and compactdisposition of all parts carrying ultrahigh frequency currents. It willbe observed from the illustrations that the longitudinal axis of thecylindrical housing, 38, and that of the tube, 30, coincides, and thatthe longitudinal axis of the dipole antenna intersects that of the tubehousing at a point substantially in line with the base of the'ultra-highfrequency tube. A

.mounting flange, 40, provided with holes, 4!,

motor shaft 21, or means by which a similarly constructed transmittingunit may be secured to semaphore arm, 5. A watertight washer or disc,43, may be placed between the flange, 40, and the coacting flange toefiectively render a completely watertight unit. The leads for the unitmay preferably be brought out through an opening at the center of thewatertight washer, 43. Since the unit need only be moved through anangle of 90 degrees or less, a flexible cable, 84, may be employed toefiect connections between the ultrahigh frequency unit and theassociated apparatus. In the transmitting unit provision may be made formounting an additional ultra-high frequencytube 30a, shown in dottedlines, directly below tube 30 as illustrated in Figure 10. The two tubesmay be thus arranged in a symmetrical parallel electrical connection, sothat the current flow through the tubes is divided and the operatinglife thereby prolonged. Further, in the event of heater failure,6f onetube the second erative functions of. the system. One preferred circuitfor the generation and radiation of polarized ultra-high frequencyenergy is illustrated in Figure llin which the two quarter wave sectionsof a-dipole H, are connected to the anode and grid circuits, 45 and 66,respectively of the oscillator tube, 47. A variable condenser, 48, maybe employed between the grid and'anode circuits as shown to effect adegree of tuning; Anode and grid'choke coils 49 and 50-, respectively,are con-. nected in series in the anode and grid leads of the suitablesource of anode E. M. F. A by-pass condenser, 58, is connected betweenthe anode .side of resistor, 56, and the cathode to complete thecircuit. A relay 59 may be placed in series in one lead of battery 53 soas to efiect on and oil. control of the transmitter in accordance withthe operation of the railroad semaphore. dent that batteries need not beemployed to supply the necessary power for the operation of the Y axisof the dipole, 6| 4 is at right angles to the axis eration, theultra-high frequency oscillator, 60,

microwave transmitter since such power may be derived in any well knownmanner-from connections with a-lighting main or other power source.

In another preferred embodiment 'of the invention illustrated inFigures12 to 22, inclusive, in which ultra-high frequency signal controlof automobile trafilc is effected, a microwave oscillator unit, 60,Figures 12 to 14, inclusive, with associated horizontal dipole radiator,5|, constructed in a manner similar to that heretofore described, isinstalled in a fixed position on the top of a conventional automobiletrafiic light housing, 63, as illustrated. In this position, thetransmitting unit is so disposed that the longitudinal of the projectedlight rays from the correlated signal lights, 64 and'65. In thispreferred embodiment of theinvention, a plurality of control signalshaving different frequencies such as 100 and 500 cycles, for example,are employed to modulate the output of the ultra-high frequencyoscillator in accordance with the correlated projection of traificcontrol lights of different colors as will be. explained in more detailhereinafter. In,this system, when the red light, 64, is in opismodulated by a control signal having a-frequency Fl, of approximately500 cycles for example, and when the green light, 65, is in operation,the oscillator is modulated by a control signal having a frequency F2considerably different in frequency from that of Fl, such as 100 cycles,for example. -A motor vehicle, illustrated in Figure 15, equipped with afixed horizontal dipole, 6.6, extending in a direction parallel to theaxles of the car, and an ultra-high frequency detector 61, disposed asshown at the top of the car, will receive the respective ultra-highfrequency trafiic control signals from dipole radiator, 6|, when the car'is proceeding directly towards the correlated traflic lights as will behereinafter explained.

To further increase the degree of usefuines of the invention, means maybe provided by which a trafiic oflicer may effect transmission oftelephonic messages to the interior of a moving vehicle approaching anultra-high frequency trafiic-signal It is eviloud speaker, 68, connectedareas transmitter, thereby providing" motorists,

based for) exam 1e on radioed tramc directions instructions receivedfrom an aeri observer stationed'above the city, and in a position todetermine points of maximum traflic congestion,- or to supply driverswith police department trafiic dis-' patches, highway directions, timesignals, or other intelligence. To effect these additional functions,

a hand telephone set, 69, Figure '12, is provided in the signal controlbox, It, for use in telephonically modulating the'ultra-high frequencyoscillator 60, or for use in conjunction with a police telephonecommunication system with which con- 1 trol box 10 is linked. By a.switching arrangement in the control box, the ultra-high frequencyoscillator may also be modulated by telephonic messages or signals froma central traiiic control station if desired, or by a repeatingsound-record reproducing device, such as a telegraphone l I, which maybe used to provide highway directions and to give regulation trafficwarnings such as No turns on red lights or Do not proceed until greenlight flashes. The repeating telegraphone is particularly adapted to afunction of this nature since the repeating mechanism is relativelysimple, there is no damaging wear on the record, as would be the caseshould a phonograph disc or sound film be employed forcontinuous'operation. In addition, the telegraphone possesses advantagesover other devices in that the magnetically recorded intelligence on thewire or tape may be changed at will without the necessity of replacingthe record. The cover, 12, of the signal control box, 10, bears controllever 13, as is common practice, so that the trafiic from the outside ofthe control box.

By reference to a preceding part of the specification relating to thevarying response characteristics of an ultra-high frequency receivingdipole when disposed in different angular positions with I respect tothe transmitting dipole, and by particular reference to the diagram ofFigure 16, it will be understood that a north or south bound vehicle,equipped with a fixed horizontal dipole, 66, extending in a directionparallel to that of its transverse axis, and ultra-high frequencydetectorlil with associated signal indicating devices such as neonlight, 14, and loud speaker, 68, will receive an ultra-high frequencysignal of maximum intensity from transmitting dipole, 6|, installed on atrafiic light, 63, disposed so as to control north-south traflic. If thetraffic light is red, as indicated, a correlated modulating stop" signalhaving a frequency Fl will be heard from to an amplifier, 15, whoseinput is connected to the output circuit of detector, 6'l. The distinctand predetermined tone characteristic of the ultra-high frequency stopsignal; accordingly, audibly informs the driver of the character of thetraffic signal, even though the traflic'light cannot be seen at themoment. A neon lamp 14, connected to the out- 'put of amplifier willlikewise be actuated and will give visual indication of the proximity ofan ultra-high frequency traflic control signal device. correspondingly,ii the trafflc light were green,

the received ultra-high frequency "go" signal,

having a predetermined .and characteristic frequency F2, would be heardin a north or south bound car, and, by virtue of the distinctive tone ofthe "go signal, the driver would be informed of the character of thetraflic signal ahead of the car. An east or west bound car also equippedwith a similar fixed horizontal receiving dipole, l8, and detector, 11,will, by virtue of the perpenlights may be controlled dicularrelationship between the receiving dipole, l6, and the transmittingdipole, 6|, simultaneously receive the ultra-high frequency signal fromdipole, 6|, with minimum signal intensity. Ac-

cordingly, a loud speaker 88, connected to the output of an amplifier,19, whose input circuit is connected to detector, 'll, will receiveinsuflicient energyv to permit its audible operation with the resultthat the particular ultra-high frequency trafiic control signalcorrelated with the northsouth traffic control device will noteffectively be heard in the east bound or west bound vehicle whereas atthe same moment it is clearly heard within a northbound or southboundvehicle at a point equidistant from the traflic control device. Theultra-high frequency signal will be received with increasing intensityin a north or south bound car until the traflic light, 68, is reached,after which the signal wilLdiminish quickly because of the shieldingeffect of the car body.

To control trafilc in the east-west lane, an additional traffic controllight, 8i, shown in dotted lines in Figure 16, may be installed at anadjacent corner, and a microwave oscillator, 82, with associatedhorizontal dipole radiator, 88, mounted thereon. It will be understoodfrom the foregoing description and from the diagram that when trafficlight 83 is projecting a red signal and a correlated ultra-highfrequency modulating signal of frequency Fl to the south and north forreception by north bound and south bound vehicles respectively, trafliclight, 8i, is projecting a green light and a correlated ultra-highfrequency signal of frequency F2 to the west and the east for receptionby east and west bound vehicles respectively.

Since no mutual interference is caused by differently polarized wavesfrom two ultra-high frequency transmitters of the type herein describedand since the substantially aperiodic character of the detector input.circuit does not require manual tuning in order to efliciently receivesignals from horizontally polarized ultra-high frequency transinitterstuned to various wavelengths within a few centimeters of each other thesystem of applicant inay compriseamultlplicity of ultra-high frequencytransmitters in the same city operating on an assorted number ofwavelengths in the vicinity of 50 centimeters without danger of mutualinterference. The aperiodic characteristics of the ultra-high frequencyreceivers will permit the effective reception of any of thesetransmitters as long as the receiving dipole is substantially parallelto a given transmitting dipole. Moreover, because of the directional andselectively polar- ;"ized characteristics of theradiated ultra-highfrequency signals, the possibility of interference with othercommunication services such as television or broadcasting will beminimized. In addition, it is pointed out that an ultra-high frequencytraflic control system of the type described herein is comparativelyfree from disturbances,

caused by static, electrical storms and other sources of electricalinterference and is unafiected by weather conditions.

In the present preferred embodiment of the invention as outlined in theforegoing description, electrical coordination and cooperation betweenthe operation of a given signal light and the emission of a horizontallypolarized ultrahigh frequency signal modulated by a particular frequencyis effected in a comparatively simple manner as is illustrated inschematic form in Figure 1'7, in which ultra-high frequency oscillator,68, provided with a horizontal dipole radiator, 8|, constructed in amanner similar to that shown in Figures 9 and 10,and mounted on the topof the traiiic light housing, is supplied with modulating electricalwaves of frequency Fl or F2 or with speech-modulated waves from theoutput circuit of amplifier 84, whose input is connected to anoscillator 85, such as a vacuum tube or other suitable audio frequencyoscillator, whose frequency of oscillation may be changed from onefrequency, Fl, to another frequency, F2, as may readily be accomplishedin a well known manner in an oscillatory circuit by changing the valueof condensers C1 or C2, or inductance, not shown, in the oscillatingcircuit. Changes in the value of such condensers or inductance of theoscillator are effected in the system of the invention as illustrated inFigure 17 by means of a single pole double throw switch 88 which, whenon contact cpointldli throws condenser C2 into the oscillating circuitof oscillator 85, and when on contact point 88 throws condenser C1 intothe oscillating circuit, thereby changing the period of oscillation ofoscillator 85 from one frequency F2 to a second frequency Flrespectively in accordance with the respective changes in the positionsof the switch point 88, respectively, thereby effecting emission 'of 'anultra-high frequency signal modulated by frequency F2 or Fl respectivelyin correlation to, and in cooperation with the projection of the greenor red light respectively.

A present preferred ultra-high frequency transmitting circuit employedin experimental tests of the ultra-high frequency traflic control systemis illustrated in Figure 18 in which the ultrahigh frequency circuitarrangement and functioning of the dipole radiator ll, oscillator tube41 and other associated parts of the oscillating circuit are identicalto those shown in Figure 11.- Modulation of the ultra-high frequencytransmitter in this particular embodiment of the invention may beeffected by any wellknown speech modulating circuit such as the Helsingcircuit illustrated herewith in which the anode lead of the modulatortube 95 is connected in conventional manner to one end of constantcurrent choke coil 98, disposed in series in the positive lead from asource of anode F. 91, and to the anode circuit of oscillator tube 81.Modulating signal voltage is supplied to the input circuit of themodulator tube through transformer 98 whose secondary leads areconnected to the control grid and cathode leads of the modulator tube.as shown. The primary winding of transformer 98 is connected to theoutput circuit of amplifier 84 whose input circuit is connected to theoutput circuit of control signal oscillator 85. The input of amplifier84 is also connected by means of switching unit 99 to the output circuitof microphone I88 of hand telephone set 89 or to the output circuit of arepeating'telegraphone ll, or to a telephone line l8l as desired. Thecontrol arm 13 of traflic signal control box 10, as

. described heretofore, efiects control of operation correlatedmodulation of ultra-high frequency oscillator tube 61 by control signalsof frequencies FI and F2 respectively, thereby causing selectivemodulation of the emitted horizontally polarized ultra-high frequencyradiant energy with correlated and cooperative projection of the signallights.

A preferred embodiment of a simple form of ultra-high frequencyreceiving apparatus installed on a moving vehicle, such as an automobileparticularly, and illustrated in Figures 19 to 21 inclusive employs aninsulated horizontal receiving dipole 66 secured on the outside of thevehicle at a point just above-the windshield I02 which location has adistinct advantage in that the receiving dipole is substantially in lineof sight relation to the transmitting dipole regardless of the presenceof other cars having steel bodiesof moderate height in front of thereceiv the reception of the ultra-high frequency trafiic control signal.Moreover, the location as depicted has an additional advantage in thatthe shielding efiect of the body proper, on the front of which thedipole is installed, reduces signal pick-up from an ultra-high frequencytransmitter which has been passed. The detector unit 61, shown in theillustration of Figure 19 with its cover removed, may be installed onthe interior of the car at a point substantially adjacent to the midpoint of the receiving dipole as indicated so that short leads betweenthe dipole and the input circuit of the ultra-high frequency detectortube 30, are effected. The high frequency choke coils, 3| and 32,associated with the anode and grid leads, respectively of the detectorcircuit are also included in the housing of detector unit 61 as shown..The output circuit of detector tube 30 and power supply leads areplaced in a shielded cable I03, indicated by dotted lines, which isconnected to the proper input and power supply terminals of an amplifierunit 15. Visual signal indicating devices, such as a red neon lamp I04and a green neon lamp I05, connected to suitable frequency selectivedevices, such as filters, not shown in Figure 19, operated by amplifierI5, are

located in proximity to the instrument board of the vehicle and in thedriver's line of vision as shown. A loud speaker 68 is disposed withinthe car at a point behind the instrument panel as shown or at anyeffective location, to give audible indication of the character of thetrafiic signal as heretofore described. I

A circuit diagram of such an ultra-high frequency receiver with visualand audible signal indicating system is shown in Figure 21 wherein theultra-high frequency detector circuit assosuch as electrical wavefilters tuned to respond selectively to received signals of frequency FIor F2 respectively. The output circuits of filters I09 and H areconnected to neon lamps I06 and I05, respectively, or to other suitablevisual indicating devices. The output of transformer I08 is alsoconnected to a loud speaker, 68, as shown, to give audible indication ofthe character of the traiiic light towards which the car is approach- 7ing.

A simple modification of the ultra-high frequency receiving and signalindicating system is shown in the schematic diagram of Figure 22 inwhich the output of the ultra-high frequency detector unit 61 issupplied to a suitable input circuit, such as that of the first stageaudio amplifier, of a conventional automobile broadcast receiver II I.Means are thereby provided by which the broadcast receiver may be easilyadapted to receive horizontally polarized ultra-high fre quency traificcontrol signals emitted by the horizontal transmitting dipole of theradio trafiic control device as well as customary entertainment frombroadcasting stations. Since the ultra-high frequency traffic controlsignal delivered to the audio frequency amplifier ofthe broadcastreceiver will be heard from loud speaker 68 regardless of thebroadcasting wave length to which the radio frequency and detectorcircuits of the broadcast receiver may be tuned, such a receiver, whenapproaching an ultra-high frequency trafiic control transmitter, will,without tuning adjustments on the part of the driver, provide audibleindication of the character of the traific signal superimposed on thereceived broadcast program signal and when the trafi'ic control lighthas been passed the signal from the broadcasting station alone will bereceived in a.

normal manner. By connecting the input circults of suitable frequencyselective devices, such as sharply tuned electrical wave filters I09 and,IIO ofproper design, shown in dotted lines, to

- of the exact character of the trafiic lights ahead of the car.

In a modification of the present preferred embodiment of the invention,illustrated inFigures 23 and 24, particularly adapted to a railroadsignal light system, the microwave oscillator 60 and associatedhorizontal dipole antenna 6| arranged in a protective housing similar tothat shown in preceding figures, are disposed on legs II2 secured to thetop of the supporting member II3 of the signal device wherein areembodied a plurality of signal lights, such as red light H4 and greenlight II5. A curved metallic reflector H6 is installed at .the rear ofoscillator unit to act as a means for directing and concentrating theemitted wave energy from dipole 5| in the direction of projection oflights H4 and H5. The reflector also serves as a shield to prevent the,projection ofultra-high frequency energy in a direction opposite to thatof the projected light rays from the correlated signal lights.weatherproof transmitter housing, IIT, fabricated from glass, porcelain,Bakelite or other suitable material supported by braces H8 is disposedaround oscillator unit 50 and its associated dipole radiator 5| as shownto completely shield the oscillator and antenna fromdamaging effects ofsevere storms and to prevent accumulations of radiator 6|.

An electrical heating coil II3 may be disposed as shown within housingIII to serve as a means for holding the temperature within the housingat a point high enough to prevent the within control box III which alsoembodies ultrahigh frequency signal control oscillator 35, ampliher 86,and switching means 39, arranged in electrical circuits identical tothose of Figure 18. Connections with a railroad telegraph or telephonesystem are also provided within housing III to provide a means ofcommunication between a central traflic station and the interior of thecab of the locomotive in amanner similar to that described heretofore inthat part of the specification pertaining to the illustrations ofFigures 12 and 18. A storage battery, not illustrated, installed in aweatherproof housing I20 may be provided as an emergency source of powersupply to insure the actuation of the ultra-high frequency signal systemindependent of thepower supply means employed to operate lights H4 andH5. A small battery-driven motor" generator unit, not illustrated, orother suitable source of anode potential may be installed in housingI2-I, adjacent to battery housing I20.

The operation of the ultra-high frequency signalling system of Figures23 and 24 is identical to that of the ultra-high frequency systemillustrated in Figure 18. When signal light II is'in operation, anultra-high frequency signal modulated by a control signal having afrequency Fl is emitted by dipole radiator 6| and when light H is inoperation, the ultra-high frequencysignal is modulated by a controlsignal of frequency F2, FI and F2 corresponding to the red and greensignal lights, respectively. The ultra-high frequency signals arereceived and visual and andible indication of the character of therailroad signals are provided in the cab of a locomotive equipped with ahorizontal receiving dipole and ultra-high frequency detector withassociated signal indicating equipment similar to that describedheretofore in that part of the specifications related to the diagram ofFigure 21.

A modification of the ultra-high frequency railroadsignal transmittingsystem shown in Figures 23 and 24 is illustrated in Figures 25 to '28inclusive, wherein one set ofrailroad signals I22 and I23, Figure 25,disposed so as to effect control of northbound trafflc on track A,Figure 28, employs an ultra-high frequency oscillator 60 with horizontaldipole radiator 6i disposed in front of a curved reflector I26. A secondset of railroad signals, I25 and I26, Figures 26 and 27, disposed so asto effect control of northbound traffic on parallel track B, Figure 28,employs an ultra-high frequency oscillator I21 with vertical dipoleradiator I28 disposed in front of curved reflector I29 as shown. In thisembodiment of the invention, a modulating signal oscillator similar tothat of 35, Figure 18, for generating signalling frequencies FI and F2,and amplifying and modulating means similar to those shown in Figure 18,may be installed in a housing such as that shown atl30, Figure 27,secured to the bottom of the signal light housing. Adequate support forand spacing between the ultra-high frequency oscillator such as I21 andreflector I23, is effected by means of an extension arm such as I3I,clearly shown in Figure 27, secured to housing I 30. Arm I3I, preferablyin the form of a pipe also encloses power supply and signal cablesconnecting the osciiator unit I21 with its modulator in housing I30.

The operation of the devices shown in Figures 25 to 27 inclusive issimilar to that of the devices shown in preceding figures with theexception that dipole radiator 6I emits a horizontal polarized wavemodulated by the signal frequency correlated with lights I22 and I23,and dipole radiator I28 emits a vertically polarized wave modulated bysignalling frequencies associated with lights I25 and I26, therebyprojecting two ultra-high frequency signals having differentpolarization characteristics along parallel tracks A and B. A northboundlocomotive C, Figure 28,

equipped with an adjustable receiving dipole I33- disposed in anoperative horizontal direction and provided with an ultra-high frequencydetector, I36, and associated traffic signal receiving. apparatusembodied in the invention as illustrated in the preceding figures, willreceive with maximum intensity only the ultra-high frequency signalsfrom horizontal dipole radiator 6| by vir-.

tue of the parallel relationship between the transmitting and receivingdipole as previously explained. In like manner another northboundlocomotive, D, Figure 28, proceeding in a parallel track B, equippedwith an adjustable receiving dipole I34 disposed in a vertical directionand provided with a detector, I36a, and associated signal indicatingapparatus will receive with maximum intensity only the ultra-highfrequency signals from vertical dipole radiator I26. Comparativelysimple means are thereby provided with which selective ultra-highfrequency transmission, on a common'wavelength if desired, may beeffected between. railroad signal devices controlling traffic onadjacent and parallel track and moving vehicles proceeding thereon.

One preferred arrangement of ultra-high frequency receiving apparatussuitable for use in connection with the system of Figures 25 to 28inclusive,-is shown in Figures 29 to 31 inclusive.

The adjustable receiving dipole, shown in horizontal position at I35,Figure 29, is connected to an ultra-high frequency detector unit, I36,both units I35 and I36 being installed near the'top and at the front ofthe cab of a locomotive as spectively, installed in proximity to theinstrument board of the locomotive. Means are thus provided by which aplurality. of control signals each having a different predeterminedfrequency value, such as Fl, F2, 'F3, as well as telephonic signalsemitted by an ultra-high frequency trans-' mitter of,a type such as thatshown in Figure 25, may be received in the cab of the locomotive byultra-high frequency detector I36 and thereafter separated by suitablefilter devices into the constituent modulating control signals offrequency FI, F2 and F3 to eifect selective visual Q5 energization ofsignal lights of different colors as well as audible reception of thetraffic control and speech signals.

A circuit diagram for such an ultra-high fre quency receiving and signalindicating system is:

shown in Figure 31 in which the output circuit of ultra-high frequencydetector unit I36, similar to that of Figure 21, is connected to theprimary windings of amplifying transformer 35 disposed in series in thepositive plate battery lead. The secondary windings of transformer 35are connected in well known manner to the input circuit of amplifierI3'I whose output is connected to loud speaker I38 and the excitingcoils of tuned reed filters I30, I60 and IflI. The output coils offilters I39, I40 and IBI are connected to the input circuits ofamplifiers I46, I01 and I 48, respectively, whose respective outputcircuits are connected to the windings of relays M9 I and I5Irespectively as shown. The armature contacts of relays I09, I50 and I5Iare connected in series with electric lamps I42, I63 and msrespectively, and a source of electric potential such as a storagebattery, I52, as shown. It is obvious that a time delay relay, 20, and apower and brake control relay, 29, may be added if desired to thecircuit of red lamp I32 so as to bring the train to a stop should thebrake not be applied within a predetermined time after the stop signalhas been energized.

- The operation of the circuit shown in Figure 31, is such that when anincoming modulating signal, having a control frequency FI, for example,is supplied to amplifier I37, the amplified signal is delivered to theexciting coils of tuned reed filters I39, I40 and Itl. The tunedmetallic of filter I39 which is tuned to respond to predeterminedsignalling frequency FI, is forced into sustained vibration by thesignal voltage in the exciting coils having frequency FI and a smallvoltage is thereby induced in the output coils of the filter unit inwell known manner. The filtered output voltage is then supplied to theinput circuit of amplifier I56 whose output voltage causes the actuationof relay its and the subsequent closing of thelighting circuit of redlamp I32 as may be understood readily from the circuit diagram. Sincethe tuned reeds of filters of M0 and MI are not forced into vibration bythe applied signal voltage of frequency Fl no voltage is induced in theoutput coils' of these filters, and consequently no actuating current issupplied to relays I50 and I5I controlling the operation of lamps I43and HM respectively. It is further pointed out that a sustainedelectrical wave of given frequency such as FI is necessary to effectsufilcient vibration of the reeds of the filter units to induce anoperative voltage in the output coils of the filters. Thus reception ofspeech modulated signals of constantly varying frequency and amplitudedoes not interfere with the operation of the visual signal indicatingmeans. Moreover, as tuned reed filters of the type described areextremely selective with regard to frequency response characteristicsthey thereby effect the rejection of all but the proper control signalsin the output circuits of the filter units.

For a better and further understanding of the nature of my inventionutilizing the polarized characteristic of ultra-high frequency energy insignaling systems, reference is made to my copending application SerialNo. 228,051 filed September 1, 1938, entitled Radio traffic controlsystem, which is a continuation-in-part of the instant application. Fora further and better understanding of my invention as applied to thereceiving apparatus employed by vehicles and em bodying my invention,reference is made to my copendi'ng application Serial No. 228,052 filedSeptember 1, 1938, entitledUltra-high frequency receiving system, as acontinuation-in-part of the instant application.

It will be recognized that the illustrative systems described herein arecapable of considerable modification andrearrangement without departingfrom the spirit and scope of the invention, and it is therefore to beunderstood that the following claims embrace all such modificationsand'equivalent arrangements as may fairly be construed to fall withinthe scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows: E ,1 1. In a system for controlling the movementof vehicular trafiic, a traflic control device having a plurality ofdistinctively colored trafiic signal lights disposed so as to effectcontrol of trailic in a particular lane, an ultra high frequency radiotransmitter for effecting directional spacial transmission of an emittedradio wave along said lane, a control signal generator for modulatingsaid radio wave by a signal having a frequency Fl when one of saiddistinctively colored trafilc sig- 'nal lights of said traffic controldevice is in operation and by a signal having a frequency F2 whenanother of said distinctively colored trafiic signal lights of saidtraffic control device is in operation, a switch to select for actuationone or the other of said traflic signal lights and simultaneously toselect the frequency of said control signal associated with said trafficsignal light, and an ultra high frequency radio receiver disposed on avehicle proceeding in said lane, said receiver having attached theretocorrespondingly colored signal lights controlled by frequencydiscriminating devices connected so as to effect actuation of either ofsaid lights dependent on the particular frequency of the signalmodulating said radio wave.

2. In a traflic control system in combination with sets of trafilcsignal lights for projecting light rays of distinguishing colorcharacteristics, circuit means for selectively energizing said traflicsignal lights to efiect projection of light rays having a desired colorcharacteristic, a radio transmitter for directively radiatinghorizontally polarized radio energy waves in space in the direction ofprojection of said light rays, a control signal generator for modulatingsaid radio tr'ansmitter with a plurality of control signals, means forchanging the frequency of said signal generator to effect a particularmodulation of said transmitter with a control signal simultaneously withprojection oflight rays having a particular color characteristic, radioreceiving apparatus mounted on a vehicle and responsive to saidhorizontally polarized radio energy waves, and visual signal indicatorscorresponding in color with the colors of said traific signal lightscontrolled by said receiving apparatus and operative simultaneously andin correlation with the opera-, tion of said tramc signal lights.

3. In a tramc control system, sets of traflic signal lights, meanscontrolling the projection of light rays from said sets of trafllcsignal lights for directing tramc movements in different lanes, an ultrahigh frequency radio transmitter, means for emittinghorizontally'polarized ultra high frequency radio wave energy in adirection

